Effects of Irrigation Amount on Alfalfa Yield and Quality with a Center-Pivot System

Abstract

Abstract. Irrigation amount is one of the most important factors that need to be considered in the management of center-pivot irrigation systems for alfalfa producers. In 2014 and 2015, a field study was conducted at Saiwusu, Inner Mongolia, China. Three irrigation levels (100%, 80%, 60% ET) were used to evaluate the effects of irrigation amount on alfalfa yield and quality. For assessing the effects of water distribution variation of center-pivot systems on alfalfa yield and quality, the water application depth, alfalfa yield, and quality between the first span, second span, overhang, and end gun were also compared. The results showed no significant difference in annual yield between the 100% and 80% ET irrigation levels. Compared to irrigation at 100% and 80% ET, irrigation at 60% ET caused significant reductions in yield of 10% and 11%, respectively. As the irrigation amount decreased, total crop water use significantly declined from 617 to 405 mm, and water use efficiency (WUE) increased from 21.8 to 29.8 kg ha-1 mm-1. The water production functions of alfalfa were parabolic for each harvest. The proportions of seasonal actual water applied to each cutting were approximately 25%, 32%, and 43%, with contributions to annual yield accounting for 54%, 30%, and 16%, respectively, indicating that the third harvest of alfalfa had great potential for improving WUE and saving water. Irrigation level had a noticeable effect on the relative feed value (RFV) but no effect on crude protein (CP) concentration. The 60% ET irrigation level was conductive to increased CP concentration and RFV of alfalfa but was of no help to improve alfalfa quality grade. The spatial distributions of annual yield and quality were highly related to the spatial distribution of water for the center-pivot system. The coefficients of variation (CVs) for annual yield, RFV, and CP of the whole system were 5% to 12%, 2% to 8%, and 1% to 8%, respectively, while the CVs for actual irrigation amount ranged from 11% to 13%. Over-irrigation caused by the end gun slightly increased alfalfa annual yield, but it reduced the quality and WUE. Therefore, the end gun in a center-pivot irrigation system should be carefully selected for improving the uniformity of water application. The 80% ET irrigation level in the first and second cuttings and the 60% ET irrigation level in the third cutting are recommended for alfalfa production in semi-arid regions, such as western Inner Mongolia in China. Keywords: Alfalfa, Center-pivot irrigation, Quality, Water management, Yield.

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Current Research in Land, Water, and Agroecosystems: ASABE Journals 2017 Year in Review

“…Zhao et al (2017) found that available water-holding capacity (AWC) was an effective metric for delineating zones for variablerate irrigation, and that differences in AWC influenced corn and winter wheat yields and water productivity in an alluvial flood plain in China. Alfalfa yield and crop water-use efficiency in a semi-arid region of China had greater response to irrigation application prior to the first cutting and progressively less response to applications prior to second and third cuttings (Li, M. et al, 2017); irrigation also affected relative Table 1. Summary of modeling research published in 2017 and discussed herein.…”

Influence of irrigation regimes on alfalfa dry matter yield and water productivity in a semiarid subtropical environment*

“…The deep root system in alfalfa helps to address the runoff and deep percolation problems in semiarid regions. Alfalfa is also a good candidate crop for applying deficit irrigation due to its drought stress tolerance and partial tendency to offset yield reductions with high forage quality (Lindenmayer et al, 2008(Lindenmayer et al, , 2011Ismail and Almarshadi, 2013;Jafarian et al, 2016;Cavero et al, 2017;Li et al, 2017).…”

“…Irrigation management also has been explored for increasing alfalfa yield in semiarid subtropical environments. Most of the work in both semiarid and arid irrigated and higher precipitation areas has focused on the effects of in-season irrigation modifications (Tapia and Lugg, 1986;Hancock and Dougherty, 2006;Hanson et al, 2007;Malinowski et al, 2007;Lindenmayer et al, 2008Lindenmayer et al, , 2011Abd El-Mageed and Semida, 2015;Jafarian et al, 2016;Abd El-Mageed et al, 2017;Cavero et al, 2017;Li et al, 2017;Abd El-Mageed et al, 2018). Ottman et al (1996), in the desert southwestern USA, found that winter termination of irrigation was preferable to suboptimal summer irrigation.…”